[R-pkg-devel] OpenMP on MacOS

[Hugh Parsonage]

Ensure you surround all your omp pragmas like so:

#ifdef _OPENMP
#pragma omp parallel ...
#endif

Essentially, detecting the operating system is not enough -- you need
to condition your use of OpenMP if and only if _OPENMP is available.

You should also do the same for

#if _OPENMP
#include <omp.h>
#endif

Note that this will also make your loops sequential when OpenMP is not
available.

On Mon, 7 Jun 2021 at 21:52, Konrad Krämer via R-package-devel
<r-package-devel using r-project.org> wrote:
>
> Dear all,
> I have a problem regarding OpenMP on Mac OS. Recently I submitted my package to CRAN (https://cran.r-project.org/web/packages/paropt/index.html). However, there seems to be a problem with 'fopenmp' on Mac OS using clang++. I have read many forums regarding the topic. Thus, I know that there is no support for OpenMp on Mac OS (at least using the default clang compiler).
> The error was: clang: error: unsupported option '-fopenmp'
> Is it possible to detect the operating system and set according to this the compile flags and use also a sequentiell version of the code?
> Or is there a better way to cope with this problem?
> Many thanks in advance for your help.
> Regards,
> Konrad
>         [[alternative HTML version deleted]]
>
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